Sahih Muslim | Book 30 | Hadith Number 5724

Narrated by Anas
Anas reported that Allah's Messenger (may peace be upon him) had the best disposition amongst people. He sent me on an errand one day, and I said: By Allah, I would not go. I had, however, this idea in my mind that I would do as Allah's Apostle (may peace be upon him) had commanded me to do. I went out until I happened to come across children who had been playing in the street. In the meanwhile, Allah's Messenger (may peace be upon him) came there and he caught me by the back of my neck from behind me. As I looked towards him I found him smiling and he said: Unais, did you go where I commanded you to go? I said: Allah's Messenger, yes, I am going. Anas further said: I served him for nine years but I know not that he ever said to me about a thing which I had done why I did that, or about a thing I had left as to why I had not done that.